Antenna isolation enhancement

ABSTRACT

Techniques are disclosed for providing isolation between a pair of partially overlapping antennas. An example electronic device includes a first antenna coupled to a first transceiver through a first signal path comprising a first feed, and a second antenna coupled to a second transceiver through a second signal path comprising a second feed. The first antenna and second antenna partially overlap. The example electronic device also includes compensation circuitry coupled to the first signal path and the second signal path and configured to generate a compensation signal that provides analog cancellation of an interference signal received at the second antenna from the first antenna.

TECHNICAL FIELD

This disclosure relates generally to techniques for improving isolationbetween antennas in devices containing multiple independent RF systems.Such devices may include mobile computing devices such as laptopcomputers, tablet computers, smart watches and bracelets, Internet orThings (IoT) devices, and the like.

BACKGROUND

The number of integrated wireless technologies included in mobilecomputing devices is increasing. These wireless technologies include,but are not limited to, WIFI, WiGig, and Wireless Wide Area Network(WWAN) technologies such as Long-Term Evolution (LTE). Each wirelesstechnology specifies certain certification standards that pertain toantenna isolation. At the same time, the available space within thedevice for the antennas that support these wireless technologies isshrinking, making it more difficult to maintain suitable antennaisolation. Radio Frequency (RF) filters such as Surface Acoustic Wave(SAW) filters are often used to provide antenna isolation. However, suchdevices add complexity and cost to the design of the system.Additionally, RF filters usually require some frequency separation forproper operation. Therefore, RF filters may not be suitable for adjacentfrequency bands with no guard band between them.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of an antenna system that provides enhancedisolation.

FIG. 2 is an example feed system that provides isolation between a pairof antennas.

FIG. 3 is another example feed system that provides isolation between apair of antennas.

FIG. 4 is another example feed system that provides isolation between apair of antennas.

FIG. 5 is another example feed system that provides isolation between apair of antennas.

FIG. 6 is another example feed system that provides isolation between apair of antennas.

FIG. 7 is another example feed system that provides isolation between apair of antennas.

FIG. 8 is another example feed system that provides isolation between apair of antennas.

FIG. 9 is a graph illustrating simulated isolation characteristics for apair of antennas partly sharing the same volume and fed by an antennafeed system configured to provide additional analog compensation.

FIG. 10 is a graph illustrating simulated isolation characteristics fora pair of antennas partly sharing the same volume and fed by an antennafeed system configured to provide additional analog compensation.

FIG. 11 is a graph illustrating simulated isolation characteristics fora pair of antennas partly sharing the same volume and fed by an antennafeed system configured to provide additional analog compensation.

FIG. 12 is a graph illustrating simulated isolation characteristics fora pair of antennas partly sharing the same volume and fed by an antennafeed system configured to provide additional analog compensation.

FIG. 13 is a block diagram of an electronic device with a multipleindependent RF systems.

FIG. 14 is a process flow diagram of an example method of operating anelectronic device with a multiple independent RF systems.

The same numbers are used throughout the disclosure and the figures toreference like components and features. Numbers in the 100 series referto features originally found in FIG. 1; numbers in the 200 series referto features originally found in FIG. 2; and so on.

DETAILED DESCRIPTION

The subject matter disclosed herein relates to techniques for improvingisolation between antennas. There are multiple scenarios in whichantenna isolation goals are difficult to achieve depending on the sizeof the form factor available for the antennas and the frequency bands inuse. For example, it may be desirable for a small form factor devicesuch as smart bracelet to support WiFi and cellular functionality. Insuch as small device, the inherent antenna isolation between the WiFiantenna and the cellular antenna may be as low as 5 to 8 decibels (dB).Current front-end solutions that rely on RF filters may not be suitablefor improving the antenna isolation due to the inadequacy of the guardbands between the operable frequency bands. For example, there is noguard band between the ISM band (2400 MHz to 2483.5 MHz) used for 2.4GHz WiFi and LTE band 40 (2300 MHz to 2400 MHz), and there is only a12.5 MHz guard band between the ISM band and LTE band 41 (2496 MHz to2690 MHz). As such, current RF front-end solutions that make use of SAWfilters, BAV filters, or FBAR filters for WiFi and cellular bands do notprovide sufficient co-existence performance.

The present disclosure describes a technique for enhancing antennaisolation. Embodiments of the present techniques include a pair ofantennas which partly share the same volume and exhibit a high inherentisolation. Additionally, the antenna feed system is constructed toprovide analog compensation, which further enhances the antennaisolation of the system. The combination of the two RF isolationtechniques provides high enough isolation to deal with transmissionnoise in the frequency band of the receiving device. For example, thepresent techniques are able to provide more than 40 dB RF isolationbetween WiFi and LTE RF transceiver ports within in a very small formfactor.

Additionally, the techniques described herein provide high levels ofisolation without the use of RF filters such as SAW filters. The analogcompensation system includes only passive components such as RFswitches, capacitors, and inductors and does not use signalamplification. Thus, current consumption, linearity distortion, andsignal noise are not significant. The circuitry can therefore easily becombined with existing RF transceiver front-end circuitry and topologieswithout any hardware modifications to those systems. In someembodiments, the analog compensation is configured to be tunable. Inthis way, the analog compensation can respond to the operationconditions of the wireless systems to provide enhanced performance undercertain operating conditions.

FIG. 1 is a diagram of an antenna system that provides enhancedisolation. The antenna system 100 includes a pair of overlappingantennas, referred to herein as first antenna 102 and second antenna104. The term “overlapping” refers to the fact that a portion of oneantenna crosses over a portion of the other antenna such that the twoantennas at least partly occupy a common area of the antenna plane. Bothantennas 102 and 104 are conductively coupled to a common ground plane106. The antenna system may be fabricated as planar structure, forexample, in one or more layers of a printed circuit board (PCB) or maybe formed from metal wires or strips and the like. Antenna 102 includesa resonant element 108 and a ground arm 110 coupled to the ground plane106. Antenna 104 includes a resonant element 112 and a ground arm 114coupled to the ground plane 106. In some embodiments, a passive circuitelement such as an inductor (not shown) may be coupled in series betweenthe resonant element and the ground plane, for example, between theground arm 110, 114 and the ground plane 106.

Each antenna 102 and 104 is fed using an indirect feeding technique,wherein the feed is capacitively or inductively coupled to the antenna'sresonant element. Accordingly, the system includes a first feed element116 capacitively coupled to the resonant element 108 of the firstantenna 102, and a second feed element 118 capacitively coupled to theresonant element 112 of the second antenna 104. Each feed element isconductively coupled through a transmission line 120 and 122 to arespective transceiver of a respective communication subsystem. Thetransceiver may be a circuit module mounted on the circuit board thatprovides integrated transmission and reception capabilities. However,the term transceiver as used herein more broadly refers to a circuitmodule that can provide reception capability, or transmissioncapability, or both.

The first antenna 102 overlaps the second antenna 104 at the overlappoint 124. At the overlap point 124, the first ground arm passes underthe second ground arm without making electrical contact. A conductiveinsulator may be interposed between the antennas at the overlap point124 to prevent electrical contact. In some examples, electrical contactmay be avoided by disposing all of a portion of the first antenna in aseparate layer of a multilayer PCB.

Each resonant element may be approximately a quarter wavelength long.For example, if the antennas operate at 2.4 Gigahertz, each resonantelement may be approximately 30 millimeters. The resonant elements mayextend approximately 6 millimeters out from the ground plane.

The antenna system 100 also includes a choke element 126 disposed inclose proximity to the overlap point 124. The choke element is a passiveelectrical component such as a capacitor or inductor through which thetwo antennas are coupled. In the example shown in FIG. 1, the chokeelement 126 couples the first ground arm to the second ground arm justbelow the two resonant elements. The choke element 126 electricallydecouples the two antennas by canceling electrical energy received byone resonant element from the other resonant element. In other words,electrical energy received from the first resonant element 108 at thesecond resonant element 112 is canceled out by energy transferred fromthe first resonant element 108 to the second resonant element 112through the choke point 126. The same cancelation applies in the otherdirection for energy received from the second resonant element 108 atthe first resonant element 112.

Each antenna 102 and 104 may operate independently. In some examples,the antenna 102 may be a transmitting antenna and the antenna 104 may bea receiving antenna. In some examples, both antennas operate astransmitters and receivers. The antennas may also operate at the samefrequency band or at different frequency bands. For example, the antenna102 may be configured for LTE cellular communication, while the antenna104 may be configured for WLAN communication, using a communicationprotocol such as WiFi. Other configurations are also possible.

The feed system for the antennas is configured to provide analogcompensation to further isolate the antennas 102 and 104. Variousexample feed systems are described below in relation to FIGS. 2-8.

FIG. 2 is an example feed system that provides isolation between a pairof antennas. In this example feed system 200, antenna 102 is configuredas a receiving antenna and antenna 104 is configured as a transmittingantenna. The receiving antenna 102 is coupled to the input of a LowNoise Amplifier (LNA) 202 and the transmitting antenna is coupled to theoutput of a power amplifier 204. Both antennas may be WiFi antennas, LTEantennas, or other antennas types. For example, the aggressor may be aWIFI transmitter and the victim may be the receive circuitry of LTE TDDband 40 or 41, or the aggressor may be an LTE transmitter and the victimmay be WIFI receive circuitry.

Although the antenna configuration provides some degree of isolationbetween the antennas 102 and 104, some portion of the signal transmittedby the transmitting antenna 104 will be received by the receivingantenna 102 as an interference signal. In the following examples, thesource of the interference is referred to as the aggressor and thereceiver of the interference is referred to as the victim.

The analog compensation techniques described herein work by subtractingthe aggressor signal in the signal chain before the LNA 202 of thereceiver being the victim. To do this, a portion of the transmittedsignal is coupled onto a second RF path, referred to herein as thecompensation path which includes compensation circuitry. The phase andamplitude of the coupled signal is adjusted, and the adjusted signal issubtracted from the signal received by the receive antenna 102 before itreaches the input of the LNA 202.

As shown in FIG. 2, the output of the power amplifier is coupled to apower splitter 206, which couples a portion of the transmitted signal tothe compensation path. The compensation path includes a phase shifter208 that adjusts the phase of the compensation signal. The phase shifter208 may be any suitable type of phase shifter and includes passiveelectrical components such as inductors, variable capacitors, and thelike. The phase shifter 208 may be variable to provide adaptive tuningas the transfer function between the antennas will change to due to theeffect of the head and hand in handheld devices. However, a fixed phaseshifter is also possible for fixed installations where theelectromagnetic coupling does not change.

The compensation path is coupled to the signal path of the receivingantenna 102 through the signal combiner 212. The signal combiner 212 maybe any suitable type of signal combiner, including a directional coupleror a power splitter, for example. The compensation path may be coupledto the signal path of the receiving antenna 102 at any point before theinput of the LNA 202.

The compensation path also includes an attenuator 210 that adjusts theamplitude of the compensation signal. The attenuator 210 may be anysuitable type of attenuator such a variable transistor, and the like. Inthis example, the attenuator 210 is variable. However, a fixedattenuator is also possible. Together, the phase shifter 208 andattenuator 210 adjust the compensation signal to be approximately equalin amplitude and shifted in phase by 180 degrees compared to the signalsreceived by the receive antenna 102.

In some examples, a high Q-factor filter such as a SAW filter may beincluded between the signal combiner 212 and the LNA 202. The phaseresponse for such high Q-factor filters is very rapid and difficult topredict and model, particularly at the band edge. Combining thecompensation signal into the received signal chain before it enters anyhigh Q front end filters makes it possible tune the compensation signalwithout regard for the phase response of the high Q filter. The phaseresponse of antennas typically used in mobile devices are much slowerdue to much lower Q in the frequency response between the antennas.However, the phase response and amplitude response between two antennasmay vary depending on the electromagnetic environment which changes dueto user interaction. Accordingly, the phase shifter 208 and attenuator210 may be adjustable so that the compensation signal can be adaptivelytuned to account for variations in the phase response and amplituderesponse.

FIG. 3 is another example feed system that provides isolation between apair of antennas. The example feed system 300 is similar to the feedsystem 200 of FIG. 2 and includes antenna 102 coupled to the input ofthe LNA 202, antenna 104 coupled to the output of the power amplifier204, phase shifter 208, and attenuator 210. However, the compensationpath is coupled to the signal paths of the receiving antenna andtransmitting antenna through a pair of directional RF couplers 302 and304.

A directional RF coupler is a four-port power coupling device thatcouples power flowing in one direction. The output by the poweramplifier 204 is coupled to the input port of the RF coupler 304. Mostof the signal power travels to the antenna 104 through the transmittedport of the RF coupler 304. Some percentage of the signal is transmittedto the compensation path through the coupled port of the RF coupler 304.The isolated port of the RF coupler is coupled to ground through a.resistor 306. The percentage of the transmitted signal that is coupledto the compensation path is determined by the RF coupler's couplingfactor, which may be fixed or variable.

The RF coupler 302 couples the compensation path to the signal path ofthe receiving antenna. The output of the compensation path, e.g., theoutput of the attenuator 210, is coupled to the input port of the RFcoupler 302. A percentage of the compensation signal passes to thetransmitted port of the RF coupler 302, which is coupled to groundthrough resistor 308, and a percentage of the compensation signal iscoupled to the input of the LNA 202. The phase shifter 208 andattenuator 210 adjust the compensation signal to be approximately equalin amplitude and shifted in phase by 180 degrees compared to the signalsreceived by the receive antenna 102. Depending on the coupling factorsome percentage of the signal received by the antenna 102 will also becouple to ground through the RF coupler 302.

FIG. 4 is another example feed system that provides isolation between apair of antennas. The example feed system 400 is similar to the feedsystem 300 of FIG. 3 and includes antenna 102 coupled to the input ofthe LNA 202, antenna 104 coupled to the output of the power amplifier204, phase shifter 208, and RF couplers 402 and 404 to couple thecompensation path to the signal paths of the receiving antenna andtransmitting antenna. However, in the example feed system 400, thecoupling factor of the RF couplers 402 and 404 is adjustable, and theamplitude of the compensation signal coupled to the signal path of thereceiving antenna 102 is controlled by one or both RF couplers 402 and404 rather than a separate attenuator.

FIG. 5 is another example feed system that provides isolation between apair of antennas. The example feed system 500 is similar to the feedsystem 400 of FIG. 4 and includes antenna 102, antenna 104, phaseshifter 208, and a pair of directional RF couplers 302 and 304 to couplethe compensation path to the signal paths of the receiving antenna andtransmitting antenna. Additionally, the coupling factor of the RFcouplers 402 and 404 is adjustable, and the amplitude of thecompensation signal coupled to the signal path of the receiving antenna102 is controlled by one or both RF couplers 402 and 404 rather than aseparate attenuator.

In the feed system 500, antenna 102 is coupled to a first transceiver,referred to herein as transceiver A 502, and antenna 104 is coupled to asecond transceiver, referred to herein as transceiver B 504. TransceiverA 502 and transceiver B 504 may be configured for any suitable type ofwireless communication protocol. For example, Transceiver A 502 may bean LTE front-end module and transceiver B 504 may be a WiFi module.Other configurations are also possible.

Transceiver A 502 and transceiver B 504 are both capable of transmittingand receiving wireless signals separately. Accordingly, each transceivermay be a source of interference for the other transceiver, depending onthe communication occurring at any given time. The feed system 500 issymmetric so that when the aggressor and victim roles are switchedbetween the transceivers no additional RF switching needs to beperformed to provide suitable isolation for both transceivers.Additionally, no DC power is dissipated due to resistive attenuators orpower splitters.

The feed system 500 may be configured to be adjusted based on thecurrent activity of the two wireless communication systems ascharacterized by the transmitted power levels of the two transceivers,the frequency bands at which the transceiver are operating, and others.Additionally, both couplers can be tuned symmetrically ornon-symmetrically to improve system performance for lowest powerconsumption or best RF performance. For example, there may be times whentransceiver A and transceiver B are operating at frequencies thatprovide a wide guard band. In such a scenario, high levels of additionalcompensation above the inherent isolation provided by the antennasthemselves may not be needed. Accordingly, the coupling factors of bothRF couplers could be reduced, thereby reducing the magnitude of thecompensation signal and reducing the RF power loss through the RFcouplers.

In some examples, the RF couplers may be tuned asymmetrically toincrease the sensitivity of one transceiver over another. Increasing thecoupling factor of RF coupler 402 and reducing the coupling factor of RFcoupler 404 will tend to increase the sensitivity of transceiver B, byreducing the power loss through coupler 404 while maintaining the samelevel of cancelation on the receive signal path of transceiver B. Thetradeoff is that power loss through coupler 402 will be increased. Sucha tradeoff may be beneficial if the received signal strength attransceiver A is higher than the received signal strength at transceiverB.

FIG. 6 is another example feed system that provides isolation between apair of antennas. The example feed system 600 is similar to the feedsystem 600 of FIG. 5 and includes antenna 102, antenna 104, phaseshifter 208, and a pair of adjustable directional RF couplers 302 and304 to couple the compensation path to the signal paths of the receivingantenna and transmitting antenna. The amplitude of the compensationsignal coupled to the signal path of the receiving antenna 102 iscontrolled by one or both RF couplers 402 and 404. Additionally, antenna102 is coupled to a transceiver A 502, and antenna 104 is coupled totransceiver B 504, each of which may be configured for any suitable typeof wireless communication protocol.

The feed system 600 also includes a set of bypass switches 602 configureto decouple the compensation path when operating conditions of the twotransceivers are suitable. For example, the compensation path may bedecoupled when transceiver A and transceiver B are operating atfrequencies that provide a wide guard band, or when the power lossthrough the RF couplers is determined to be detrimental. The bypassswitches 602 may be switched in unison to couple or decouple the RFcouplers. Decoupling the RF couplers disengages the compensation pathand eliminates the power loss through the RF couplers.

FIG. 7 is another example feed system that provides isolation between apair of antennas. In some cases, depending on the design of the RFcouplers, the insertion loss in the RF couplers may be high. The examplefeed system 700 reduces the losses in the system by coupling the signalpath of the aggressor to the compensation path through an RF splitterrather than an RF coupler. The example feed system 700 includes antenna102 coupled to transceiver A 502 and antenna 104 coupled to transceiverB 504. The amplitude and phase of the compensation signal is controlledby an adjustable phase shifter 208 and adjustable attenuator 210. Thesignal paths of the antennas 102 and 104 are coupled to the compensationpath by power splitters 702 and 704 and RF couplers 302 and 304. Thepower splitters may be fixed (i.e., non adjustable) asymmetric resistivepower splitters.

The feed system 700 includes a switching complex that is configurable toadjust the compensation scheme according to the activity of the twowireless communication systems. Switches 602 are bypass switches thatmay be controlled to engage or disengage the compensation path duringtimes when additional compensation is not needed. Switches 706 may becontrolled to complete the appropriate compensation path whencompensation is turned on, The switch settings shown in FIG. 7 are theswitch settings that will be activated when the transceiver A isbehaving as an aggressor toward transceiver B. In this configuration ofswitch settings, power from the transceiver A is output to the RF powersplitter 702, and a portion of the transmitted power is diverted to thecompensation path. The compensation signal is then phase adjusted by thephase shifter 208 and amplitude adjusted by the attenuator 210. Thephase and amplitude adjusted compensation signal is then output to theRF coupler 304 and combined with the signal path of the antenna 104. Thecompensated signal then bypasses the RF power splitter 704 and arrivesat transceiver B 504. During times in which transceiver B is theaggressor toward transceiver A, the switch settings for switches 706will be the opposite of what is shown in FIG. 7.

FIG. 8 is another example feed system that provides isolation between apair of antennas. The example feed system 800 is similar to the feedsystem 700 of FIG. 7 and includes antenna 102 coupled to transceiver A502, antenna 104 coupled to transceiver B 504, and adjustable phaseshifter 208 and attenuator 210 for tuning the compensation signal. Thesignal paths of the antennas 102 and 104 are coupled the compensationpath by RF couplers 302 and 304 and a pair of RF splitter networks 802and 804.

The RF power splitter networks 802 and 804 include a set of RF powersplitters 806 and a set of switches 808 that are controllable to couplea specific RF splitter 806 to the compensation path. Each RF splitter806 is configured to provide a different power coupling factor. Theselection of RF power splitter 806 is used for course tuning of thecompensation signal and depends on the level of attention needed togenerate a suitable compensation signal. Further tuning of the amplitudeof the compensation signal may be performed by the variable attenuator210. Although four RF power splitters 806 are included in each of the RFpower splitter networks 802 and 804 shown in FIG. 6, it will beappreciated that any suitable number of RF power splitters may beincluded depending on the design of a particular embodiment, including2, 3, 5 or more RF power splitters.

Switches 602 are bypass switches that may be controlled to engage ordisengage the compensation path during times when additionalcompensation is not needed. The switches 706 may be controlled incoordination with the switches 808 to complete the appropriatecompensation path when compensation is turned on depending on whichtransceiver is the aggressor and which transceiver is the victim.

The switch settings shown in FIG. 8 are the switch settings that will beactivated when the transceiver A is behaving as an aggressor towardtransceiver B. In this configuration of switch settings, power from thetransceiver A is output to the RF power splitter A, and a portion of thetransmitted power is diverted to the compensation path. The compensationsignal is then phase adjusted by the phase shifter 208 and amplitudeadjusted by the attenuator 210. The phase and amplitude adjustedcompensation signal is then output to the RF coupler 304 and combinedwith the signal path of the antenna 104. The compensated signal thenbypasses the RF power splitter network 804 and arrives at transceiver B504. During times in which transceiver B is the aggressor towardtransceiver A, the switch settings for switches 706 and 808 will be theopposite of what is shown in FIG. 8.

FIG. 9 is a graph illustrating simulated isolation characteristics for apair of antennas partly sharing the same volume and fed by an antennafeed system configured to provide additional analog compensation. Theline 902 shows the signal level, S21, received at the victim from theaggressor. The antennas system represented in FIG. 9 is tuned to providehigh levels of isolation between the antennas at the 2.4 Gigahertz (GHz)WiFi band and the LTE band 3 (1.8 GHz). This configuration may beselected based on the actual operating frequencies of the two antennas,for example, if one antenna is a WLAN antenna operating at 2.4 GHz andthe other antenna is operating at LTE band 3.

As can be seen in FIG. 9, approximately 40 to 50 dB of isolation isprovided between the antennas across the 2.4 GHz WiFi band. Thisisolation is due primarily to the physical configuration of theoverlapping antennas and the choke element as described in FIG. 1.Additionally, approximately 40 to 60 dB of isolation is provided betweenthe antennas across the LTE band 3. The isolation in the LTE band is dueprimarily to the feed system, which in this example generates acompensation signal phase shifted by 330 degrees. The compensationsignal generated by the feed system can be tuned to provide varyingisolation characteristics as shown in FIGS. 10-12.

FIG. 10 is a graph illustrating simulated isolation characteristics fora pair of antennas partly sharing the same volume and fed by an antennafeed system configured to provide additional analog compensation. Theline 1002 shows the signal level, S21, received at the victim from theaggressor. The antennas system represented in FIG. 10 is tuned toprovide high levels of isolation between the antennas at the 2.4Gigahertz (GHz) WiFi band and the LTE band 2 (1.9 GHz).

In this example, the feed system generates a compensation signal phaseshifted by 290 degrees. This shifts the peak LTE isolation level to LTEband 2 and provides approximately 40 to over 60 dB isolation across theentire LTE band 2. Additionally, the phase shift of the compensationsignal improves the isolation across the 2.4 GHz WiFi, providingapproximately 40 to over 60 dB isolation.

FIG. 11 is a graph illustrating simulated isolation characteristics fora pair of antennas partly sharing the same volume and fed by an antennafeed system configured to provide additional analog compensation. Theline 1102 shows the signal level, S21, received at the victim from theaggressor. The antennas system represented in FIG. 11 is tuned toprovide high levels of isolation between the antennas at the 2.4Gigahertz (GHz) WiFi band and the LTE band 1 (2.1 GHz).

In this example, the feed system generates a compensation signal phaseshifted by 270 degrees. This shifts the peak LTE isolation level to LTEband 1 and provides approximately 40 to over 80 dB isolation across theentire LTE band 2. Additionally, the phase shift of the compensationsignal reduces the isolation across the 2.4 GHz WiFi, but still providesapproximately 40 to 55 dB isolation.

FIG. 12 is a graph illustrating simulated isolation characteristics fora pair of antennas partly sharing the same volume and fed by an antennafeed system configured to provide additional analog compensation. Theline 1202 shows the signal level, S21, received at the victim from theaggressor. The antennas system represented in FIG. 12 is tuned toprovide high levels of isolation between the antennas at the 2.4Gigahertz (GHz) WiFi band and the LTE band 40 (2.3 GHz).

In this example, the feed system generates a compensation signal phaseshifted by 200 degrees. This shifts the peak LTE isolation level to LTEband 40, which is adjacent to the 2.4 GHz WiFi band. This phase shiftresults in greater than 40 dB isolation across both bands.

FIG. 13 is a block diagram of an electronic device with a multipleindependent RF systems. The electronic device 1300 may be, for example,a tablet computer, mobile phone, smart phone, or a smart watch, amongothers. The electronic device 1300 may include a central processing unit(CPU) 1302 that is configured to execute stored instructions, as well asa memory device 1304 that stores instructions that are executable by theCPU 1302. The CPU may he coupled to the memory device 1304 by a bus1306. Additionally, the CPU 1302 can be a single core processor, amulti-core processor, a computing cluster, or any number of otherconfigurations. Furthermore, the electronic device 1300 may include morethan one CPU 1302. The memory device 1304 can include random accessmemory (RAM), read only memory (ROM), flash memory, or any othersuitable memory systems. For example, the memory device 1304 may includedynamic random access memory (DRAM).

The electronic device 1300 may also include a graphics processing unit(GPU) 1308. As shown, the CPU 1302 may be coupled through the bus 1306to the GPU 1308. The GPU 1308 may be configured to perform any number ofgraphics operations within the electronic device 1300. For example, theGPU 1308 may be configured to render or manipulate graphics images,graphics frames, videos, or the like, to be displayed to a user of theelectronic device 1300.

The electronic device 1300 can also include a storage device 1310. Thestorage device 1310 is a non-volatile physical memory such as a harddrive, an optical drive, a flash drive, an array of drives, or anycombinations thereof. The storage device 1310 can store user data, suchas audio files, video files, audio/video files, and picture files, amongothers. The storage device 1310 can also store programming code such asdevice drivers, software applications, operating systems, and the like.The programming code stored to the storage device 1310 may be executedby the CPU 1302, GPU 1308, or any other processors that may be includedin the electronic device 1300.

The electronic device 1300 can also include a display 1312 and one ormore user input devices 1314, such as switches, buttons, a keyboard, amouse, or trackball, among others. One of the input devices 1314 may bea touchscreen, which may be integrated with the display 1312.

The electronic device 1300 also includes transceivers 1316 and feedsystem 1318. The transceivers 1318 may be any of the transceiversdescribed above in FIGS. 1-12. Similarly, the feed system 1318 may beany of the feed systems described above in relation to FIGS. 1-12. Thefeed system includes the compensation circuitry described above forenhancing the isolation between antennas 102 and 104.

The programming code stored to the storage device 112 may include a feedsystem controller 1320. The feed system controller 1320 is configured tocontrol the feed system 1318 to adapt the compensation circuitry of thefeed system 1320 to changing conditions as described above. For example,the feed system 1318 may be configured to control the compensationcircuitry to engage or disengage compensation, adjust the compensationlevels, adjust the phase of the compensation signal, and the like. Insome examples, rather than being implemented as programming code storedto the storage device 1312, the feed system controller 1320 may beimplemented as firmware or logic circuits included in one or morededicated processors such as an Application Specific Integrated Circuit(ASIC), a Field Programmable Gate Array (FPGA), a System on a Chip(SOC), and combinations thereof.

The block diagram of FIG. 13 is not intended to indicate that theelectronic device 1300 is to include all of the components shown in FIG.13. Rather, the computing system 1300 can include fewer or additionalcomponents not shown in FIG. 13, depending on the details of thespecific implementation. Furthermore, any of the functionalities of theCPU 1302, or the graphics processor 1308 may be partially, or entirely,implemented in hardware and/or in a processor. For example, thefunctionality may be implemented in any combination of ApplicationSpecific Integrated Circuits (ASICs), Field Programmable Gate Arrays(FPGAs), logic circuits, and the like.

FIG. 14 is a process flow diagram of an example method of operating anelectronic device with a multiple independent RF systems. The method1400 may be performed by the electronic device 1300 and implemented bycircuitry included in the transceivers 1316, the feed system 1318, andthe feed system controller 1320. The circuitry may be embodied inhardware, such as logic circuitry or one or more processors configuredto execute instructions stored in a non-transitory, computer-readablemedium.

At block 1402, a transmit signal is sent to a first antenna along afirst signal path comprising a first feed, which may be an indirectfeed. At block 1404, a receive signal is received from a second antennaalong a second signal path comprising a second feed, which may be anindirect feed. In some examples, the first antenna and second antennapartially overlap as shown in FIG. 1. At block 1406, a portion of thetransmit signal is coupled to a compensation circuitry to generate acompensation signal. At block 1408, a phase of the compensation signalis adjusted by the compensation circuitry. At block 1410, the adjustedcompensation signal is coupled to the second signal path to provideanalog cancelation of an interference signal received at the secondantenna from the first antenna.

The method 1400 should not be interpreted as meaning that the blocks arenecessarily performed in the order shown. Furthermore, fewer or greateractions can be included in the method 1400 depending on the designconsiderations of a particular implementation.

EXAMPLES

Example 1 is an electronic device with a plurality of independent RadioFrequency (RF) systems. The system includes a first antenna coupled to afirst transceiver through a first signal path including a first feed,and a second antenna coupled to a second transceiver through a secondsignal path including a second feed. The first antenna and secondantenna partially overlap. The system includes compensation circuitrycoupled to the first signal path and the second signal path andconfigured to generate a compensation signal that provides analogcancelation of an interference signal received at the second antennafrom the first antenna.

Example 2 includes the system of example 1. In this example, the systemincludes a choke element that couples the first antenna and the secondantenna at a location where the first antenna and the second antennaoverlap.

Example 3 includes the system of any one of examples 1 to 2. In thisexample, the compensation circuitry includes a variable phase shifter, avariable attenuator, a first directional coupler to couple thecompensation circuitry to the first signal path, and a seconddirectional coupler to couple the compensation circuitry to the secondsignal path,

Example 4 includes the system of any one of examples 1 to 3. In thisexample, the compensation circuitry includes a variable phase shifter, afirst adjustable directional coupler to couple the compensationcircuitry to the first signal path, and a second adjustable directionalcoupler to couple the compensation circuitry to the second signal path.

Example 5 includes the system of any one of examples 1 to 4. In thisexample, the compensation circuitry includes an adjustable directionalcoupler to couple the compensation circuitry to the first signal path,wherein a coupling factor of the adjustable directional coupler isadjustable to control a magnitude of the compensation signal.

Example 6 includes the system of any one of examples 1 to 5. In thisexample, the system includes a set of switches to decouple thecompensation circuitry from the first signal path and the second signalpath.

Example 7 includes the system of any one of examples 1 to 6. In thisexample, the compensation circuitry includes a Radio Frequency (RF)power splitter to couple the compensation circuitry to the first signalpath, and a directional coupler to couple the compensation circuitry tothe second signal path.

Example 8 includes the system of any one of examples 1 to 7. In thisexample, the compensation circuitry includes an RF power splitternetwork to couple the compensation circuitry to the first signal pathand a directional coupler to couple the compensation circuitry to thesecond signal path, wherein the RF power splitter network includes aplurality of RF power splitters with different power coupling factors,wherein one of the plurality of RF power splitters is selected toprovide a course tuning of the amplitude of the compensation signal.

Example 9 includes the system of any one of examples 1 to 8. In thisexample, the first transceiver is a Wireless Local Area Network (WLAN)transceiver and the second transceiver is a cellular communicationstransceiver.

Example 10 includes the system of any one of examples 1 to 9. In thisexample, the compensation circuitry is configured to adjust a phase ofthe compensation signal depending on an operating frequency of the firsttransceiver or the second transceiver or both.

Example 11 is a method of operating an electronic device with aplurality of independent Radio Frequency (RF) systems. The methodincludes sending a transmit signal to a first antenna along a firstsignal path including a first feed, and receiving a receive signal froma second antenna along a second signal path including a second feed. Thefirst antenna and second antenna partially overlap. The method alsoincludes coupling a portion of the transmit signal to a compensationcircuitry to generate a compensation signal; adjusting a phase of thecompensation signal via the compensation circuitry. The method alsoincludes coupling the adjusted compensation signal to the second signalpath to provide analog cancelation of an interference signal received atthe second antenna from the first antenna.

Example 12 includes the method of example 11. In this example, the firstantenna and the second antenna are coupled by a choke element at alocation where the first antenna and the second antenna overlap.

Example 13 includes the method of any one of examples 11 to 12. In thisexample, the method includes adjusting a magnitude of the compensationsignal via a variable attenuator included in the compensation circuitry.

Example 14 includes the method of any one of examples 11 to 13. In thisexample, coupling a portion of the transmit signal to the compensationcircuitry includes coupling the transmit signal to the compensationcircuitry through a directional coupler.

Example 15 includes the method of any one of examples 11 to 14. In thisexample, coupling a portion of the transmit signal to the compensationcircuitry includes coupling the transmit signal to the compensationcircuitry through a variable directional coupler, the method includingadjusting a coupling factor of the variable directional coupler toadjust a magnitude of the compensation signal.

Example 16 includes the method of any one of examples 11 to 15. In thisexample, coupling a portion of the transmit signal to the compensationcircuitry includes coupling the transmit signal to the compensationcircuitry through a Radio Frequency (RF) power splitter.

Example 17 includes the method of any one of examples 11 to 16. In thisexample, coupling a portion of the transmit signal to the compensationcircuitry includes coupling the transmit signal to the compensationcircuitry through an RF power splitter network including a plurality ofRF power splitters, the method including selecting one of the pluralityof RF power splitters provide a course tuning of a magnitude of thecompensation signal.

Example 18 includes the method of any one of examples 11 to 17. In thisexample, the method includes decoupling the compensation circuitry fromthe first signal path and the second signal path to deactivate theanalog cancellation.

Example 19 includes the method of any one of examples 11 to 18. In thisexample, the first transceiver is a Wireless Local Area Network (WLAN)transceiver and the second transceiver is a cellular communicationstransceiver.

Example 20 includes the method of any one of examples 11 to 19. In thisexample, adjusting a phase of the compensation signal includes adjustingthe phase based on an operating frequency of the first transceiver orthe second transceiver or both.

Example 21 is a tangible, non-transitory, computer-readable mediumincluding instructions that are executable by a processor. Thecomputer-readable medium includes instructions that direct the processorto couple a portion of a transmit signal to a compensation circuitry togenerate a compensation signal. The transmit signal is sent from a firsttransceiver to a first antenna along a first signal path including afirst feed. The computer-readable medium also includes instructions thatdirect the processor to adjust a phase of the compensation signal andcouple the adjusted compensation signal to a second signal path. Thesecond signal path couples a receive signal received from a secondantenna to a second transceiver through a second feed. The first antennaand second antenna partially overlap. The adjusted compensation signalprovides analog cancelation of an interference signal received at thesecond antenna from the first antenna.

Example 22 includes the computer-readable medium of example 21. In thisexample, the computer-readable medium includes instructions that directthe processor to control a compensation circuitry to adjust a magnitudeof the compensation signal via a variable attenuator included in thecompensation circuitry.

Example 23 includes the computer-readable medium of any one of examples21 to 22. In this example, the computer-readable medium includesinstructions that direct the processor to control a compensationcircuitry to adjust a magnitude of the compensation signal via avariable directional coupler that couples the first signal path thecompensation circuitry.

Example 24 includes the computer-readable medium of any one of examples21 to 23. In this example, the computer-readable medium includesinstructions that direct the processor to control a compensationcircuitry to select one of a plurality of Radio Frequency (RF) powersplitters of an RF power splitter network to couple the first signalpath to the compensation circuitry and provide a course tuning of amagnitude of the compensation signal.

Example 25 includes the computer-readable medium of any one of examples21 to 24. In this example, the computer-readable medium includesinstructions that direct the processor to control a compensationcircuitry to decouple the compensation circuitry from the first signalpath and the second signal path to deactivate the analog cancellation.

Example 26 includes the computer-readable medium of any one of examples21 to 25. In this example, the computer-readable medium includesinstructions that direct the processor to control a compensationcircuitry to adjust the phase of the compensation signal based on anoperating frequency of the first transceiver or the second transceiveror both.

Example 27 includes the computer-readable medium of any one of examples21 to 26. In this example, the computer-readable medium includesinstructions that direct the processor to control a compensationcircuitry to adjust the phase of the compensation signal based on achange in the transfer function between the first antenna and the secondantenna.

Example 28 is an apparatus with a plurality of independent RadioFrequency (RF) systems. The apparatus includes means for sending atransmit signal to a first antenna along a first signal path, and meansfor receiving a receive signal from a second antenna along a secondsignal path. The first antenna and second antenna partially overlap. Theapparatus also includes means for coupling a portion of the transmitsignal to a compensation circuitry to generate a compensation signal,means for adjusting a phase of the compensation signal via thecompensation circuitry, and means for coupling the adjusted compensationsignal to the second signal path to provide analog cancelation of aninterference signal received at the second antenna from the firstantenna.

Example 29 includes the apparatus of example 28. In this example, thefirst antenna and the second antenna are coupled by a choke element at alocation where the first antenna and the second antenna overlap.

Example 30 includes the apparatus of any one of examples 28 to 29. Inthis example, the apparatus includes means for adjusting a magnitude ofthe compensation signal via a variable attenuator included in thecompensation circuitry.

Example 31 includes the apparatus of any one of examples 28 to 30. Inthis example, the means for coupling a portion of the transmit signal tothe compensation circuitry includes a directional coupler.

Example 32 includes the apparatus of any one of examples 28 to 31. Inthis example, the means for coupling a portion of the transmit signal tothe compensation circuitry includes a variable directional coupler,wherein a coupling factor of the variable directional coupler isadjustable to control a magnitude of the compensation signal.

Example 33 includes the apparatus of any one of examples 28 to 32. Inthis example, the means for coupling a portion of the transmit signal tothe compensation circuitry includes an RF power splitter.

Example 34 includes the apparatus of any one of examples 28 to 33. Inthis example, the means for coupling a portion of the transmit signal tothe compensation circuitry includes an RF power splitter networkincluding a plurality of RF power splitters, wherein one of theplurality of RF power splitters is selected to provide a course tuningof a magnitude of the compensation signal.

Example 35 includes the apparatus of any one of examples 28 to 34. Inthis example, the apparatus includes means for decoupling thecompensation circuitry from the first signal path and the second signalpath to deactivate the analog cancellation.

Example 36 includes the apparatus of any one of examples 28 to 35. Inthis example, the means for sending includes a Wireless Local AreaNetwork (WLAN) transceiver and the means for receiving includes acellular communications transceiver.

Example 37 includes the apparatus of any one of examples 28 to 36. Inthis example, the means for adjusting the phase of the compensationsignal adjusts the phase based on an operating frequency of the firsttransceiver or the second transceiver or both.

Some embodiments may be implemented in one or a combination of hardware,firmware, and software. Some embodiments may also be implemented asinstructions stored on the tangible non-transitory machine-readablemedium, which may be read and executed by a computing platform toperform the operations described. In addition, a machine-readable mediummay include any mechanism for storing or transmitting information in aform readable by a machine, e.g., a computer. For example, amachine-readable medium may include read only memory (ROM); randomaccess memory (RAM); magnetic disk storage media; optical storage media;flash memory devices; or electrical, optical, acoustical or other formof propagated signals, e.g., carrier waves, infrared signals, digitalsignals, or the interfaces that transmit and/or receive signals, amongothers.

An embodiment is an implementation or example. Reference in thespecification to “an embodiment,” “one embodiment,” “some embodiments,”“various embodiments,” or “other embodiments” means that a particularfeature, structure, or characteristic described in connection with theembodiments is included in at least some embodiments, but notnecessarily all embodiments, of the present techniques. The variousappearances of “an embodiment,” “one embodiment,” or “some embodiments”are not necessarily all referring to the same embodiments.

Not all components, features, structures, characteristics, etc.described and illustrated herein need be included in a particularembodiment or embodiments. If the specification states a component,feature, structure, or characteristic “may”, “might”, “can” or “could”be included, for example, that particular component, feature, structure,or characteristic is not required to be included. If the specificationor claim refers to “a” or “an” element, that does not mean there is onlyone of the element. If the specification or claims refer to “anadditional” element, that does not preclude there being more than one ofthe additional element.

It is to be noted that, although some embodiments have been described inreference to particular implementations, other implementations arepossible according to some embodiments. Additionally, the arrangementand/or order of circuit elements or other features illustrated in thedrawings and/or described herein need not be arranged in the particularway illustrated and described. Many other arrangements are possibleaccording to some embodiments.

In each system shown in a figure, the elements in some cases may eachhave a same reference number or a different reference number to suggestthat the elements represented could be different and/or similar.However, an element may be flexible enough to have differentimplementations and work with some or all of the systems shown ordescribed herein. The various elements shown in the figures may be thesame or different. Which one is referred to as a first element and whichis called a second element is arbitrary.

It is to be understood that specifics in the aforementioned examples maybe used anywhere in one or more embodiments. For instance, all optionalfeatures of the computing device described above may also be implementedwith respect to either of the methods or the computer-readable mediumdescribed herein. Furthermore, although flow diagrams and/or statediagrams may have been used herein to describe embodiments, thetechniques are not limited to those diagrams or to correspondingdescriptions herein. For example, flow need not move through eachillustrated box or state or in exactly the same order as illustrated anddescribed herein.

The present techniques are not restricted to the particular detailslisted herein. Indeed, those skilled in the art having the benefit ofthis disclosure will appreciate that many other variations from theforegoing description and drawings may be made within the scope of thepresent techniques. Accordingly, it is the following claims includingany amendments thereto that define the scope of the present techniques.

1. An electronic device, comprising: a first transceiver coupled to afirst antenna via a first signal path; a second transceiver coupled to asecond antenna via a second signal path; and compensation circuitrycoupled to the first signal path and to the second signal path, thecompensation circuitry configured to generate a compensation signal thatprovides analog cancellation of an interference signal received via thefirst antenna from the second antenna, the interference signal beingreceived at the first signal path as a result of the secondtransceiver's transmission, and the interference signal being coupledfrom the second antenna to the first antenna causing the firsttransceiver to be potentially subjected to the interference signal,wherein the compensation circuitry includes an adjustable attenuatorconfigured to couple the first signal path to the second signal path,and wherein the adjustable attenuator is configured to electronicallyadjust an amplitude of the compensation signal based upon a transmissionpower level used by the second transceiver.
 2. The electronic device ofclaim 1, wherein the compensation circuitry further comprises: avariable phase shifter configured to adjust a phase of the compensationsignal to represent a phase shift of 180 degrees compared to a phase ofthe interference signal.
 3. The electronic device of claim 2, whereinthe variable phase shifter is configured to adjust the phase of thecompensation signal based upon an operating frequency of the firsttransceiver and/or the second transceiver.
 4. The electronic device ofclaim 1, wherein the compensation circuitry further comprises: a radiofrequency (RF) power splitter configured to couple a portion of atransmit signal on the second signal path, which is a result of thesecond transceiver's transmission, to the adjustable attenuator.
 5. Theelectronic device of claim 1, wherein the compensation circuitry furthercomprises: a signal combiner coupled to the first signal path betweenthe first antenna and an input of a low noise amplifier (LNA) that iscoupled to the first transceiver, and wherein the signal combiner isconfigured to subtract the compensation signal from a receive signal onthe first signal path, which is received via the first antenna, toprevent the interference signal from being provided to the input of theLNA.
 6. The electronic device of claim 1, wherein the compensationcircuitry further comprises: a first radio frequency (RF) couplerconfigured to couple the compensation signal to the first signal path;and a second radio frequency (RF) coupler configured to couple a portionof a transmit signal on the second signal path, which is a result of thesecond transceiver's transmission, to the adjustable attenuator.
 7. Theelectronic device of claim 1, wherein the compensation circuitry furthercomprises: a first radio frequency (RF) power splitter network coupledto the first signal path, the first RF power splitter network includinga plurality of first RF power splitters, each one of the plurality offirst RF power splitters having a different respective coupling factor;and a second radio frequency (RF) power splitter network coupled to thesecond signal path, the second RF power splitter network including aplurality of second RF power splitters, each one of the plurality ofsecond RF power splitters having a different respective coupling factor,and wherein the a selection of respective ones of the first RF powersplitters and the second RF power splitters enables a further adjustmentto the amplitude of the compensation signal.
 8. A feed system,comprising: a first signal path coupled between a first antenna and afirst transceiver; a second signal path coupled between a second antennaand a second transceiver; and compensation circuitry coupled to thefirst signal path and to the second signal path, the compensationcircuitry configured to generate a compensation signal that providesanalog cancellation of an interference signal received via the firstantenna from the second antenna, the interference signal being receivedat the first signal path as a result of the second transceiver'stransmission, and the interference signal being coupled from the secondantenna to the first antenna causing the first transceiver to bepotentially subjected to the interference signal, wherein thecompensation circuitry includes an adjustable attenuator configured tocouple the first signal path to the second signal path, and wherein theadjustable attenuator is configured to electronically adjust anamplitude of the compensation signal based upon a transmission powerlevel used by the second transceiver.
 9. The feed system of claim 8,wherein the compensation circuitry further comprises: a variable phaseshifter configured to adjust a phase of the compensation signal torepresent a phase shift of 180 degrees compared to a phase of theinterference signal.
 10. The feed system of claim 9, wherein thevariable phase shifter is configured to adjust the phase of thecompensation signal based upon an operating frequency of the firsttransceiver and/or the second transceiver.
 11. The feed system of claim8, wherein the compensation circuitry further comprises: a radiofrequency (RF) power splitter configured to couple a portion of atransmit signal on the second signal path, which is a result of thesecond transceiver's transmission, to the adjustable attenuator.
 12. Thefeed system of claim 8, wherein the compensation circuitry furthercomprises: a signal combiner coupled to the first signal path betweenthe first antenna and an input of a low noise amplifier (LNA) that iscoupled to the first transceiver, and wherein the signal combiner isconfigured to subtract the compensation signal from a receive signal onthe first signal path, which is received via the first antenna, toprevent the interference signal from being provided to the input of theLNA.
 13. The feed system of claim 8, wherein the compensation circuitryfurther comprises: a first radio frequency (RF) coupler configured tocouple the compensation signal to the first signal path; and a secondradio frequency (RF) coupler configured to couple a portion of atransmit signal on the second signal path, which is a result of thesecond transceiver's transmission, to the adjustable attenuator.
 14. Thefeed system of claim 8, wherein the compensation circuitry furthercomprises: a first radio frequency (RF) power splitter network coupledto the first signal path, the first RF power splitter network includinga plurality of first RF power splitters, each one of the plurality offirst RF power splitters having a different respective coupling factor;and a second radio frequency (RF) power splitter network coupled to thesecond signal path, the second RF power splitter network including aplurality of second RF power splitters, each one of the plurality ofsecond RF power splitters having a different respective coupling factor,and wherein the a selection of respective ones of the first RF powersplitters and the second RF power splitters enables a further adjustmentto the amplitude of the compensation signal.
 15. An electronic device,comprising: a first transceiver coupled to a first antenna via a firstsignal path; a second transceiver coupled to a second antenna via asecond signal path; and compensation circuitry coupled to the firstsignal path and to the second signal path, the compensation circuitryconfigured to generate a compensation signal that provides analogcancellation of an interference signal received via the first antennafrom the second antenna, the interference signal being received at thefirst signal path as a result of the second transceiver's transmission,and the interference signal being coupled from the second antenna to thefirst antenna causing the first transceiver to be potentially subjectedto the interference signal; and a first adjustable directional couplerconfigured to couple the compensation circuitry to the first signalpath, wherein the first adjustable directional coupler is configured toelectronically adjust an amplitude of the compensation signal based upona transmission power level used by the second transceiver.
 16. Theelectronic device of claim 15, wherein the compensation circuitryfurther comprises: a variable phase shifter configured to adjust a phaseof the compensation signal to represent a phase shift of 180 degreescompared to a phase of the interference signal.
 17. The electronicdevice of claim 16, wherein the variable phase shifter is configured toadjust the phase of the compensation signal based upon an operatingfrequency of the first transceiver and/or the second transceiver. 18.The electronic device of claim 16, wherein the compensation circuitryfurther comprises: a second adjustable directional coupler configured tocouple a portion of a transmit signal on the second signal path, whichis a result of the second transceiver's transmission, to the firstadjustable directional coupler via the variable phase shifter.
 19. Theelectronic device of claim 18, further comprising: a set of bypassswitches configured to decouple the compensation circuitry from thefirst signal path and from the second signal path when the secondtransceiver is not transmitting as an aggressor to the firsttransceiver, the decoupling of the compensation circuitry from the firstsignal path and the second signal eliminating power loss through thefirst adjustable directional coupler and the second adjustabledirectional coupler.
 20. A feed system, comprising: a first signal pathcoupled between a first antenna and a first transceiver; a second signalpath coupled between a second antenna and a second transceiver;compensation circuitry coupled to the first signal path and to thesecond signal path, the compensation circuitry configured to generate acompensation signal that provides analog cancellation of an interferencesignal received via the first antenna from the second antenna, theinterference signal being received at the first signal path as a resultof the second transceiver's transmission, and the interference signalbeing coupled from the second antenna to the first antenna causing thefirst transceiver to be potentially subjected to the interferencesignal; and a first adjustable directional coupler configured to couplethe compensation circuitry to the first signal path, wherein the firstadjustable directional coupler is configured to electronically adjust anamplitude of the compensation signal based upon a transmission powerlevel used by the second transceiver.
 21. The feed system of claim 20,wherein the compensation circuitry further comprises: a variable phaseshifter configured to adjust a phase of the compensation signal torepresent a phase shift of 180 degrees compared to a phase of theinterference signal.
 22. The feed system of claim 21, wherein thevariable phase shifter is configured to adjust the phase of thecompensation signal based upon an operating frequency of the firsttransceiver and/or the second transceiver.
 23. The feed system of claim20, wherein the compensation circuitry further comprises: a secondadjustable directional coupler configured to couple a portion of atransmit signal on the second signal path, which is a result of thesecond transceiver's transmission, to the first adjustable directionalcoupler via the variable phase shifter.
 24. The feed system of claim 23,further comprising: a set of bypass switches configured to decouple thecompensation circuitry from the first signal path and from the secondsignal path when the second transceiver is not transmitting as anaggressor to the first transceiver, the decoupling of the compensationcircuitry from the first signal path and the second signal eliminatingpower loss through the first adjustable directional coupler and thesecond adjustable directional coupler.